Re: [PATCH] patch-slab-split-03-tail

From: Anton Blanchard (anton@samba.org)
Date: Fri Oct 04 2002 - 19:14:34 EST


> <<<<<<<
> An object cache's CPU layer contains per-CPU state that must be
> protected either by per-CPU locking or by disabling interrupts. We
> selected per-CPU locking for several reasons:
> [...]
> x Performance. On most modern processors, grabbing an uncontended
> lock is cheaper than modifying the processor interrupt level.
> <<<<<<<<
>
> Which cpus have slow local_irq_disable() implementations? At least for
> my Duron, this doesn't seem to be the case [~ 4 cpu cycles for cli]

Rusty did some tests and found on the intel chips he tested
local_irq_disable was slower. He posted the results to lkml a few weeks
ago.

On ppc64 it varies between chips.

Anton
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